Coolant leak from under the car HELP !!!

MHDBMW12 · 03-29-2022, 06:16 PM

Hi saw this hard plastic hose that runs across the subframe underneath the car. Looks to be cracked and leaking. “Coolant return line.” Is what ECS tuning calls it. Wondering if it’s the right part not sure if that’s correct. Also if you guys have seen any how-to’s?

e90yyc · 03-29-2022, 07:21 PM

That’s one of its names—yes. Coolant crossover pipe is another.

Most cooling system how-tos are: drain, disconnect, replace, refill.

No different with this part. There are two bolts holding it to the steering rack that can be a pain to remove, but otherwise it’s just a matter of disconnecting each fitting, which as you probably know can be a real pain. I recently did this job and can’t remember there being anything particularly tricky or noteworthy.

This hose connects the heater return line to the coolant expansion tank, thermostat, and in the case of auto transmission cars, it also attaches to transmission fluid heat exchanger.

Edit: There’s a third 10mm bolt on the driver side, but I don’t think it attaches to the rack. Can’t remember where it threads into, but you’ll need to remove it too.

MHDBMW12 · 03-29-2022, 07:59 PM

Quote:

Originally Posted by e90yyc

That’s one of its names—yes. Coolant crossover pipe is another.

Most cooling system how-tos are: drain, disconnect, replace, refill.

No different with this part. There are two bolts holding it to the steering rack that can be a pain to remove, but otherwise it’s just a matter of disconnecting each fitting, which as you probably know can be a real pain. I recently did this job and can’t remember there being anything particularly tricky or noteworthy.

This hose connects the heater return line to the coolant expansion tank, thermostat, and in the case of auto transmission cars, it also attaches to transmission fluid heat exchanger.

Do you know if its any harder with the xdrive version? cause everything is more difficult with xdrive.

e90yyc · 03-30-2022, 01:14 AM

Probably about the same. It’s likely (but not certain) the three 10mm bolts are easier to access on the RWD cars, but truthfully it’s not that bad on xDrive. You’ll want a ratcheting box-end wrench though, if I’m remembering right. You can get by with just a regular 10mm though.

03-29-2022, 06:16 PM	#1
MHDBMW12 Private First Class 13 Rep 178 Posts Drives: BMW 335Xi Join Date: Mar 2022 Location: Calgary iTrader: (0)	Coolant leak from under the car HELP !!! Hi saw this hard plastic hose that runs across the subframe underneath the car. Looks to be cracked and leaking. “Coolant return line.” Is what ECS tuning calls it. Wondering if it’s the right part not sure if that’s correct. Also if you guys have seen any how-to’s? Last edited by MHDBMW12; 03-29-2022 at 06:42 PM..
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03-29-2022, 07:21 PM	#2
e90yyc Art Collector 2427 Rep 3,450 Posts Drives: 2007 328xi (GM-delete 6MT) Join Date: Feb 2018 Location: Canada iTrader: (0)	That’s one of its names—yes. Coolant crossover pipe is another. Most cooling system how-tos are: drain, disconnect, replace, refill. No different with this part. There are two bolts holding it to the steering rack that can be a pain to remove, but otherwise it’s just a matter of disconnecting each fitting, which as you probably know can be a real pain. I recently did this job and can’t remember there being anything particularly tricky or noteworthy. This hose connects the heater return line to the coolant expansion tank, thermostat, and in the case of auto transmission cars, it also attaches to transmission fluid heat exchanger. Edit: There’s a third 10mm bolt on the driver side, but I don’t think it attaches to the rack. Can’t remember where it threads into, but you’ll need to remove it too. __________________ When I'm dead, just throw me in the trash. Last edited by e90yyc; 03-30-2022 at 01:11 AM..
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03-30-2022, 01:14 AM	#4
e90yyc Art Collector 2427 Rep 3,450 Posts Drives: 2007 328xi (GM-delete 6MT) Join Date: Feb 2018 Location: Canada iTrader: (0)	Probably about the same. It’s likely (but not certain) the three 10mm bolts are easier to access on the RWD cars, but truthfully it’s not that bad on xDrive. You’ll want a ratcheting box-end wrench though, if I’m remembering right. You can get by with just a regular 10mm though. __________________ When I'm dead, just throw me in the trash.
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